Apple's line of MacBook Pro laptops was intended for the professional and power users. The MacBook Pro line includes the MacBook Pro 13" Unibody, MacBook Pro 15", MacBook Pro 15" Unibody, MacBook Pro 17", and the MacBook Pro 17" Unibody.

First, make sure the case you purchased was fully-tested and in working condition when you bought it (I've purchased 100+ cases on eBay, and I'd say a solid 1/3 of them are bad or not fully tested). Providing the case is good and fully-functional, I would re-seat the keyboard cable. Next, I would test the top case by installing the battery, prompting the orange/amber LED light on the charger, and then resetting the PMU by pressing the left "shift", "control", and "option" keys along with the power button all at the exact same time for at least 5 seconds. If you see the charging light turn from orange to green, then you know that at least the power button is good, and the laptop "should" power on. One other thing to try, is to unplug the top case cable from the logic board and try "jumping" the board using the two power-pads near the keyboard connector. I have experienced top cases that appeared good, but were shorted to the point where they would cause the computer not to turn on (despite the PMU resetting).